1. Field of the Invention
The present invention generally relates to an oil well pump and more particularly a reciprocating plunger type pump having beams for exerting a downward force on the pump plunger to facilitate its downward movement without exerting compressive forces on the pump rod and a desander for preventing accumulation of sand in the bottom of the plunger.
2. Description of the Prior Art
Oil well pumps of the reciprocating plunger type are well known and employed in many installations. Examples of such pumps are found in prior U.S. Pat. Nos. 3,143,080, issued Aug. 4, 1964, and 3,765,482, issued Oct. 16, 1973. In present pumps, the pump plunger is reciprocated by a pump rod usually constructed from a plurality of connected sucker rods extending to ground level and connected with an actuating mechanism such as a walking beam which oscillates in a vertical plane. When pumping heavy oil or heavy oil, the plunger, when moving downwardly in the pump barrel, is retarded by the heavy oil which some times results in lateral flexing of the pump rod which causes the rod to engage the inner wall of the production tubing thus resulting in excessive wear to the pump rod and the production tubing and also results in reduced production due to the retarded movement of the plunger. Additionally, when pumping fluid having sand entrained therein, the bottom of the plunger which is normally hollowed and tapered toward the traveling valve in the plunger causes the sand to compact in the lower end of the plunger and in some instances clog or bridge across the hollow plunger, thus further restricting flow of oil through the plunger on the down stroke.